Browsing by Author "Zhao, Li"

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A first near real-time seismology-based landquake monitoring system
(2017-03-02)
Chao, Wei-An
;
Wu, Yih-Min
;
Zhao, Li
;
Chen, Hongey
;
Chen, Yue-Gau
Hazards from gravity-driven instabilities on hillslope (termed 'landquake' in this study) are an important problem facing us today. Rapid detection of landquake events is crucial for hazard mitigation and emergency response. Based on the real-time broadband data in Taiwan, we have developed a near real-time landquake monitoring system, which is a fully automatic process based on waveform inversion that yields source information (e. g., location and mechanism) and identifies the landquake source by examining waveform fitness for different types of source mechanisms. This system has been successfully tested offline using seismic records during the passage of the 2009 Typhoon Morakot in Taiwan and has been in online operation during the typhoon season in 2015. In practice, certain levels of station coverage (station gap < 180 degrees), signal-to-noise ratio (SNR >= 5.0), and a threshold of event size (volume > 10(6) m(3) and area > 0.20 km(2)) are required to ensure good performance (fitness > 0.6 for successful source identification) of the system, which can be readily implemented in other places in the world with real-time seismic networks and high landquake activities.
The Large Greenland Landslide of 2017: Was a Tsunami Warning Possible?
(2018-07-01)
Chao, Wei-An
;
Wu, Tso-Ren
;
Ma, Kuo-Fong
;
Kuo, Yu-Ting
;
Wu, Yih-Min
Tsunamis generated by mass movements such as landslides, underwater slumps, and rock avalanches can lead to serious inundation of nearby populated areas. The lack of timely estimations of the moving mass volume, however, makes providing operational early warnings for landslides particularly challenging. In June 2017, a large landslide in Greenland generated tsunami waves of about 1 m high that impacted the small town of Nuugaatsiaq. We show how the seismic analysis of real-time seismic records from the Greenland Ice Sheet Monitoring Network (GLISN) can provide estimates of essential physical properties of the landslide such as collapse mass and sliding velocity shortly after origin time. The estimation of the landslide source parameters can be utilized for tsunami-wave simulations. We demonstrate how the real-time integration of seismic waveform inversion with forward tsunami-wave simulation could have enabled a timely operational warning (about 10 min) before the arrival of the impending tsunami waves at the village of Nuugaatsiaq.